Nesting biology of the spectacled eider Somatera fischeri (Brandt) on the Yukon-Kuskokwim Delta, Alaska

Abstract

Nesting biology of the Spectacled Eider Somateria fischeri (Brandt) on the Yukon-Kuskokwim Delta, Alaska, was studied in 1972 and 1973. These data are compared with data from 1969, 1970, and 1971 (Eisenhauer et al. 1971, Eisenhauer and Frazer 1972, and Mickelson 1973). Paired, the birds arrived mostly from the north within a 3-4 day period in mid-May. Before 7 June, 80 percent of the nests were initiated. Located on islands, shorelines and peninsulas, most nests were within 7 feet of water. Rate of egg laying was 1/day (mean clutch size 4.5 eggs). Incubation lasted 24 days. Hatching took place from 20 June to 10 July (nesting success range 35 percent to 83 percent). Timing of nest site availability appears to dictate clutch size and reproductive success. Ducklings are raised on shallow freshwater ponds within 1.5 miles of their nest site.